1. Field of the Invention
The present invention relates to heat exchange units which are adapted to transfer heat between a heat transfer fluid flowing through a heat exchanger and air passing thereover. More specifically, the present invention relates to a wrapper for encasing a heat exchange unit. In particular, this invention concerns means for fastening the wrapper and the location of louver openings within the wrapper such that the wrapper may provide structural support.
2. Description of the Prior Art
Heat exchange units to be mounted external of a residence or an enclosure are found in the air conditioning industry. These units typically have a heat exchanger and a fan for circulating air through the heat exchanger in heat exchange relation with refrigerant flowing through the heat exchanger. A suitable base, grille, and top cover are typically provided to encase the unit. Depending upon the application a compressor, four-way valve and controls may also be included within this outdoor unit.
When a conventional plate fin coil is utilized within an outdoor heat exchange unit the plate fin coil is often bent in a U or circular shape to provide a large surface area within a compact unit. Conventionally, a fan is mounted such that external air is drawn into the unit through the heat exchanger and exhausted out the top of the unit. These plate fin coils are structurally solid and usually serve to support the weight of the top cover to which the fan may be mounted. A grille formed from welded wire is mounted about the surface of the heat exchanger to prevent physical contact with the heat exchanger itself.
When a slit fin heat exchanger, as described below, is used instead of plate fin coils the structural integrity of plate fin coil is not maintained. Slit finned heat exchangers are formed from a long continuous tube having a U-shaped segmented fin helically wrapped thereabout to form a heat exchange surface having a myriad of heat exchange projections extending from the surface of the tube. This continuous tube may then be formed to the desired heat exchanger configuration such as a cylinder and secured within a heat exchange unit to provide for heat transfer between a heat transfer medium such as refrigerant flowing therethrough and air flowing thereover. Since there are no tube sheets nor plate fin structure connecting various tubes to each other there is no inherent structure to support the rows of slit fin tubing making up the cylindrical heat exchanger or to support the components of the unit.
The wrapper disclosed herein is designed to encase a slit fin coil and to have solid portions which may provide structural support for the unit. Additionally, the wrapper has closure means which cooperate with a fastening strip to secure the wrapper in position. Furthermore, the use of a wrapper having louvered portions as disclosed herein may obviate the necessity of painting the coil since utilizing these louver openings instead of the previous welded wire grille results in the heat exchanger being substantially hidden from view. Consequently it is the exterior surface of the wrapper rather than the heat exchanger which becomes esthetically important.